San Bernardino County, California air quality history
Daily Air Quality Index summaries from EPA monitors in San Bernardino, California, 1980–2025.
13%
Good days in 2025
77
Median daily AQI, 2025
110
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for San Bernardino, California on 365 days. 46 of those days (13%) were in the Good range, and the median daily AQI was 77. That median is higher than the typical monitored county in California (median 45.5 across 46 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 225 days. Across the years with fuller monitoring, the share of Good days rose: an average of 8% in 1980–1982 versus 12% in 2023–2025.
How the days broke down each year
Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.
Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous
Typical and high-end AQI over time
The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.
Median daily AQI
90th-percentile daily AQI
Main pollutant by day, 2025
On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.
Pollutant
Days as main pollutant
Share of monitored days
Ozone
225
62%
Fine particles (PM2.5)
125
34%
Coarse particles (PM10)
11
3%
Nitrogen dioxide (NO₂)
4
1%
Year-by-year data
Annual AQI summary by year
Year
Days with AQI
Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous
Median AQI
90th pct.
Max AQI
Main pollutant
2025
365
46
209
67
39
4
0
77
156
207
Ozone
2024
366
40
182
56
61
26
1
87
185
593
Ozone
2023
365
50
197
67
44
7
0
71
164
214
Ozone
2022
365
23
212
67
56
7
0
77
166
225
Ozone
2021
365
17
202
73
61
11
1
87
172
486
Ozone
2020
366
33
170
76
69
18
0
93
185
236
Ozone
2019
365
29
203
71
54
8
0
81
172
213
Ozone
2018
365
14
197
96
51
7
0
89
164
221
Ozone
2017
365
9
209
73
51
23
0
84
185
233
Ozone
2016
366
9
219
78
48
12
0
84
172
217
Ozone
2015
365
14
221
88
37
5
0
84
154
223
Ozone
2014
365
21
217
83
43
1
0
82
159
201
Ozone
2013
365
35
195
83
49
3
0
84
159
218
Ozone
2012
366
20
203
84
51
8
0
90
169
207
Ozone
2011
365
21
197
83
57
7
0
84
166
233
Ozone
2010
365
12
218
80
48
7
0
84
164
219
Ozone
2009
365
52
173
66
66
8
0
84
179
224
Ozone
2008
366
71
148
67
55
25
0
84
190
222
Ozone
2007
365
61
145
78
66
15
0
90
179
234
Ozone
2006
365
60
162
67
56
20
0
81
179
239
Ozone
2005
365
61
151
73
54
26
0
83
185
242
Ozone
2004
366
61
137
86
60
22
0
91
182
242
Ozone
2003
365
64
137
63
50
51
0
91
209
251
Ozone
2002
365
44
155
72
59
33
2
90
200
409
Ozone
2001
365
33
156
91
56
29
0
100
195
241
Ozone
2000
366
48
151
75
74
18
0
95
179
246
Ozone
1999
365
16
163
85
72
29
0
101
192
239
Ozone
1998
365
67
149
62
32
55
0
87
223
296
Ozone
1997
365
67
121
77
61
39
0
96
201
240
Ozone
1996
366
45
143
69
39
70
0
100
221
272
Ozone
1995
365
56
115
77
44
73
0
103
222
273
Ozone
1994
365
48
118
54
41
104
0
108
239
292
Ozone
1993
365
49
98
61
57
100
0
119
235
284
Ozone
1992
366
59
89
53
41
123
1
126
239
550
Ozone
1991
365
14
109
93
42
107
0
116
240
297
Ozone
1990
365
21
101
94
45
103
1
119
244
357
Ozone
1989
365
28
96
67
42
132
0
143
251
297
Ozone
1988
366
25
116
49
34
142
0
126
263
298
Ozone
1987
365
32
115
48
38
132
0
122
255
298
Ozone
1986
365
23
107
65
42
128
0
133
264
298
Ozone
1985
365
36
104
58
43
124
0
122
266
298
Ozone
1984
366
19
122
48
40
137
0
136
268
300
Ozone
1983
365
40
121
56
26
122
0
108
275
300
Ozone
1982
365
44
107
65
25
124
0
108
264
300
Ozone
1981
365
26
88
68
23
160
0
151
284
300
Ozone
1980
366
18
118
61
23
145
1
126
285
336
Ozone
What this data can and can’t tell you
It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.
It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.
Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.
Counties in California with a similar median AQI in 2025
